Waterproofing composition



, iness or stickiness in Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE DOUGLAS FRANK TWISS, OF

ERIDINGTON, BIRMINGHAM, LIMITED, A BRITISH COMPANY WATERPROOFING COMPOSITION No Drawing. Application filed May 19, 1930, Serial No. 453,856,

Our invention relates to improvements in waterproofing compositions suitable as protective coatings for articles of fibrous materials such as paper, papier-mach and millboard. More particularly it relates to a waterproofing composition that is suitable for containers of fibrous material's.

When a container of cellulosic or fibrous material is to be waterproofed against aqueous compositions offood stuff it is desirable to avoid tackiness or stickiness that is characteristic of unvulcanized rubber. The use of vulcanized rubber, or such rubber that comes into contact with aqueous or water containing food stuff, is objectionable because such vulcanized rubber usually contains zinc compounds that have been used as accelerators of vulcanization.

An object of the present invention is to overcomethe above disadvantages and objections to the use of rubber a's waterproofing and to provide a waterproofing for fibrous or paper-like material that does not require vulcanization and has characteristics suitable for use in contact .with food materials.

A further object of the invention is to provide a container having a waterproofing surface or layer that may be sealed to a cover or cap by warming.

In accordance with our invention a waterproofing surface or layer is formed on the fibrous material to be coated by depositing the dispersed particles from an aqueous emulsion or dispersion that contains in addition to the rubber material a vegetable or mineral wax or a mixture of suitable waxes or similar material. The presence of the Wax serves to eliminate or prevent any tackthe deposit thus formed and thus obviates the necessity for subsequent vulcanization.

The emulsions or dispersions may be made of any suitable rubber material and may consist of or contain gutta-percha, balata or similar vegetable resins occurring natuand in Great Britain June 26, 1929.

rally or artificially obtained. The dispersions may be in concentrated form. Such a concentrated form of latex may, for example, be obtained by stabilizing an ammonia preserved latex with a stabilized or protective colloid such as oleic acid or soap and subsequently concentrated or agitated as described in Patent 1,846,164, granted Feb. 23, 1932.

The following example illustrates how the process can be effected. A latex-emulsified wax mixing having the following composition of solids I Rubber Parafiin wax parts by weight 50 parts by weight is prepared in known manner in the presence of suitable protectlve collolds such as casein, gum acacia or soap.

The interiors of the containers may be conveniently coated by filling the containers with the latex-emulsified wax mixing, allowing to stand for five minutes to permit air bubbles to escape, inverting and allowing the containers to drain and subsequently drying the adhering layers in a warm atmosphere.

The containers may also be coated both internally and/or externally by such known methods as dipping, spreading or spraying.

Where lids are to be applied these according to shape may be coated with the above aqueous emulsions or dispersions by any one or more of the aforementioned methods and then applied to the containers.

The containers may then be sealed, e. g. by merely warming after placing the lids thereon or by application of additional emulsion or dispersion round the sealing space with subsequent drying.

The invention is not limited to the coating of shaped or formed cellulosic or fibrous material, but is also applicable to the coating of surfaces of cellulosic or fibrous material in the form of sheets.

What we claim is: 1. A composition for coating cellulosic or brous materials which consists of an aqueous v dispersion of rubber material admixed with 5 an aqueous dispersion of wax in substantially equal proportions of wax and rubber.

he composition of wax is an inert claim 1 in which the mineral wax.

In witness whereof, we have hereunto 10 s1gned our names.

DOUGLA WALTE S FRANK TWISS. R GEORGE GORHAM. 

